Rare stick insect to go international to save its species

By Bridie Smith Science Editor

Hundreds of precious Lord Howe Island stick insect eggs will be sent overseas as part of a captive breeding program for the critically endangered Australian insect – which until 2001 was thought extinct.

Bred at Melbourne Zoo, 900 of the lentil-sized eggs will travel to zoos in Bristol, Toronto and San Diego, where insurance populations will be established for one of the world's rarest insects.

A vibrant green juvenile Lord Howe Island stick insect.

Photo: Eddie Jim

The international captive breeding programs will rely on the expertise developed in Melbourne, where zoo staff pioneered the captive breeding and handling of the prehistoric-looking insect.

The eggs are the twelfth generation to be bred in captivity. All are descended from a breeding pair known as Adam and Eve, which were rescued from a volcanic outcrop off Lord Howe Island known as Ball's Pyramid on Valentine's day in 2003.

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Some of the Lord Howe Island stick insect eggs, which are being sent to three overseas zoos as part of a captive breeding program.

Photo: Eddie Jim

The first batch of 300 eggs will fly out to Bristol on Wednesday, carefully packed in batches of 50 eggs dispersed through sterilised sand. They will travel in a climate-controlled part of the cargo hold, where temperatures are kept between 18 and 22 degrees.

Invertebrate keeper Rohan Cleave said while more than 12,000 insects had been bred from the original pair, there was no guarantee that there would be similar success overseas.

However he said it was critical to try and establish other populations as an insurance measure, given the precarious existence of the insect in the wild, where only about 40 are thought to live.

"If there was an issue (at Melbourne Zoo) because of disease or a health crash, then that's basically it," he said. "We could lose the species."

In order to be allowed into Canada, America and England, strict biosecurity measures had to be adhered to – including "disinfecting" the eggs before they travelled.

Melbourne Zoo vet Sarah Frith said it took months to establish a way to make sure the eggs didn't carry any diseases or other risks – while also ensuring they remained viable.

Lord Howe Island stick insect eggs are being sent to three overseas zoos as part of a captive breeding program.

Photo: Eddie Jim

The new system of disinfecting involves washing the eggs in a mild bleach solution before rinsing them in sterilised water and then air drying them. It has been trialled at the zoo with a batch of hatchlings proof it was a success.

Dr Frith said the eggs were laid at varying times and could hatch anytime between a week to three months after arrival.

‘’If there was an issue (at Melbourne Zoo) because of disease or a health crash, then that’s basically it ... We could lose the species.’’

Rohan Cleave

When they emerge from the egg, the insects are a vibrant green and three times the size of the egg. It makes for a difficult entrance into the world, as Rohan Cleave has captured on film.

Over time the stick insects moult, turning a mottled green, then brown and finally jet black.

Stick insects are among renowned naturalist Sir David Attenborough's favourite creatures. He collected them as a child. In 2012, he went out of his way to see a Lord Howe Island stick insect in Melbourne.